CA1329590C

CA1329590C - Mixed hydrophobe polymers

Info

Publication number: CA1329590C
Application number: CA000614201A
Authority: CA
Inventors: Arjun Chandra Sau
Original assignee: Aqualon Co
Current assignee: Aqualon Co
Priority date: 1988-10-03
Filing date: 1989-09-28
Publication date: 1994-05-17
Anticipated expiration: 2011-05-17
Also published as: US4904772A; JPH02169601A; JP2950868B2; BR8905021A; ATE120764T1; EP0362769B1; DE68922058D1; EP0362769A1; DE68922058T2

Abstract

MIXED HYDROPHOBE POLYMERS

Abstract of the Disclosure Water-soluble, cellulose ether polymers having (a) at least one substituent selected from the group consisting of hydroxyethyl, hydroxypropyl, and methyl radicals and (b) two or more hydrophobic radicals having 6 to 20 carbon atoms, in which one of the hydrophobic radicals has a carbon chain length that is at least two carbon atoms longer than that of another of the hydrophobic radicals, and their use in aqueous protective coatings, such as latex paints, are disclosed.

Description

~

0871p(FF) 1 3 2 9 5 9 0 This invention relates to water~soluble cellulose derivatives and aqueous ~olutions containing the same. Moxe specifically, it xelate to water soluble, cellulo~e ethex polymexs ~ubstituted with hydxoxyethyl, hydxoxypxopyl, and methyl radicals and at lfeast two hydxophobic xadicals, and theix use in aqueous protective coatings, such as latex paints.
~ .S. Patent 4,228,277, discloses water soluble cellulqse ethex polymexs substituted with (a) ~ethyl, hydxoxyethyl or hydxoxypxopyl xadicals, and (b) C10 to C24 long chain alkyl gxoups (hydxophobes). U.S. Patent ~To. 4,352,916, discloses modifying such cellulose ethexs with hydrophobes having 6 to 25 carbon atoms.
Neithex of these patents discuss using hydrophobes of dif~exent lengths in combination (mixed hydxophobes). All of the exa~ples shown therein are directed to cellulose ethexs modified with chains having a unifoxm length, except those used in examples 7 to 10 of U.S. Patent No. 4,228,277 and example 4 of UOS. Patent No. 4! 352,916 whexein epoxides having 20 ~o 24 caxbon atoms wexe used. (Epoxides having 20 to 24 carbon atoms wexe used because it is difficult to sepaxate compounds having caxbon chains of that oxdex o~
length).
The above~described cellulose ethers are used as thickenexs in aqueous liquids, paxticularly including latex paints. The water~301ubility and paint xheological pxoper~
tie~ of the~e polymexs axe pximaxily dictated by the si~e and amount of the hydxophobe. Por instance, a hydxoxyethyl~
cellulose dexivative having a long alkyl chain hydxophobe (chain length of 12 ox more) exhibits vexy high aqueous vi3cosity at a much lower alkyl content than its shortex .

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~` 1 32q590 alkyl chain (8 or less carbon atoms~ containing counterparts.
However, simllar polymers havlng long alkyl chains become water-insoluble at a lower level of alkyl substitution. This lnsolu-blllty severely restrlcts thelr usefulness ln situations where a hlgher hydrophobe level is best suited to achleve the desired performance properties, as for lnstance, irnproved color develop-ment and spatter reslstance ln palnt. Hence, there has been a desire to develop cellulose polymers havlng such hydrophobes that provide enhanced vlscoslty and deslred rheologlcal properties, wlthout being insoluble ln water.
Nonlonlc cellulose ether polymers having at least one substituent selected from the group consisting of hydroxyethyl, hydroxypropyl and methyl radlcals and a 3-alkoxy-2-hydroxypropyl group wherein the alkyl moiety ls a stralght chaln alkyl group are described in, e.g., U.S. Patent No. 4,845,207. These polymers also suffer from the lnsolublllty problem referred to above.
There ls a need for cellulose ethers havlny hydrophobes wlth the enhanced rheologlcal propertles and improved control ~ -required to overcome the dlsadvantages of the known polymers.
According to the lnvention, a water-soluble, cellulose ether polymer havlng (a) at least one substituent selected from the group conslstlng of hydroxyethyl, hydroxypropyl, and methyl radicals and (b~ two or more hydrophoblc radlcals ha~lng 6 to 20 carbon atoms selected from the group conslstlng of long chain alkyl, alphahydroxyalkyl, urethane, acyl and 3-alkoxy-2-hydroxy-propyl, ls characterlzed ln that one of the hydrophoblc radicals has a carbon chaln length that is at least two carbon atoms longer than that of the another of the hydrophoblc radlcals, the , - -, - ~

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~ 329590 2a 22124-1745 hydrophobic radlcals are contained ln a total amount of at least about 0.2 welght percent, and the cellulose ethers are at least 1%
by weight soluble in water.
The polymers of thls inventlon are substantially com-pletely soluble in water at ambient temperature. They can be prepared directly from cellulose or from cellulose ether deriva-tives, such as hydroxyethylcellulose.

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Chemical cotton, wood pulp and other souxces of cellulose that axe useful in the manufacture of the polymers of thiæ invention (as well as the aforementioned polymers) are readily available.
For the polymexs of this invention to be prepaxed from any of the well known cellulose ether dexivatives, the polymex must have a reasonably accessible reactive hydroxyl gxoup. Pxeferxed poly~exs are anionic or nonionic, with the lattex being moxe pxefexxed. Such polymers include hydroxy~
ethylcellulos~, hydxoxypropylcellulose, methylcellulose, hydroxypxopylmethylcellulose (al~o known as methylhydxoxy-pxopylcellulose), methylhydroxyethylcellulose (also known as hydroxyethylmethylcellulose), ethylhydxoxyethylcellulose, hydroxypxopylhydroxyethylcellulose, carboxymethylhydroxy~
ethylcellulose, hydroxybutylhydroxyethyicellulose and theix dexivatives. Com~ercially available materials that can be used to pxepaxe the polymexs of this invention include those available under the txademaxks Natxosol and Klucel, by Aqualon Company, Wilmington, DE, Culminal by Aqualcn Company and Aqualon GmbH & Co. KG, Dusseldoxf, Federal Republic of Germany, Blanose by Aqualon Fxance BV, Alizayt France, and Methocel, by Dow Chemical ~ompany, Midland, MI.
Prefexred axe poly~ers containing hydroxyethyl and hydxoxypropyl gxoups~ In a moxe preferred polymex the substituent (a) is hydroxyethyl, and the cellulose ethex derivative is nonionic and has a hydroxyethyl molar substitution (M.S.) (number of moles of substituent per cellulosic anhydroglucose unit in the cellulose molecule) of about 1.0 to 4.5. Most pxefexably the polymex has a viscosity in the range of about 5 to about 60,000 centipoise (cps) in a 1 weight ~ solution using a ~xookfield Synchxo~
Lectxic Model LVF Viscometer at 6 rpm (Brookfield LVF
Viscosity~.
Th~ hydrophobic groups of this invention include long chain alkyl gxoups dexived from alkyl halides, alphahydxoxy-alkyl radicals dexived from epoxides, urethane radicals derived fxo~ isocyanates, acyl radicals derived fxom acids or acyl chlorides, and 3~alkoxy~2~hydroxypxopyl radicals derived 1 32~590 ~ 4 ~

fxom alkylglycidyl ethers. Preferxed axe hydrophobic gxoups derived fxom alkyl bromides and 3~alko~y~2~hydxoxypropyl xadicals.
In some instances, the hydxophobic radicals are not entixely comprised of the same numbex of caxbon atoms. Fox instance r alkyl glycidyl ethexs used to pxepaxe 3-alkoxy~
2~hydroxy~propyl polymexs axe available as, e.g., C12~13 and C15~1~ alkyl glycidyl ethexs. Hexein, such xadicals are not conside~ed hydrophobic gxoups having a diffexent number of caxbon atoms.
Methods of pxeparing mixed ethexs of cellulose, i.e., pxoducts having more than one e~hexifying ~odifiex at~ached to the same cellulose chain axe known to the axt. The pxoducts of this invention can be pxepaxed via essentially the ~ame methods. Fox example, the pxefexred pxoceduxe fox pxepaxing a polymex using alkyl bxomides compxises alkylyzation of cellulose in a mixtuxe of t~butyl alcohol, i~opxopyl alcohol, acetone, water and sodium hydroxide in a nitxogen atmosphexe fox a pexiod of time that is sufficient to distxibute the alkali onto the cellulose. Then, ethylene oxide is added to the alkali cellulose sluxxy, followed by heating at 70C for 1 houx. The xesulting sluxxy is paxtially neutxalized and additional ethylene oxide is added to the xeaction mixtuxe. Then, the resulting xeaction mixtuxe is heated at 90~95C for 90 minutes. Caustic and alkyl bxomides (two different alkyl bxomides, one having at least two more carbon atoms than the other) axe added, followed by heating of the xeaction mixtuxe at 115C fox 2 houxs and neutralization of the xeaction mixture. The resultant polymer is then puxified by washing the reaction mixtuxe.
Polymexs containing a 3~alkoxy-2~hydxoxypxopyl radical can be pxepaxed in a similar mannex. Bxiefly, modification can be effected by slurxying a polymex, such as hydxoxy~
ethylcellulose, in an inext oxganic diluent such as a lowex aliphatic alcohol, ketone, ox hydrocaxbon and adding a solu~
tion of alkali metal hydroxide to the xesultant sluxxy at low tempexature. When the ethex is thoroughly wetted and swollen 1 32~590 ~ 5 ~

by the alkali, the alkylglycidyl ether is added and the xeaction is continued with agitation and heating until complete. Residual alkali is then neutrali~ed and the pxoduct is xecovered, washed with inext diluents, and dried.
The polymers of this invention can also be pxepaxed di~ctly fxom cellulose. ~or instance, polymer containing 3~alkoxy~2~hydxoxypxopyl and hydxo~yethyl xadicals can be pxepaxed by first adding chemical cotton to a mixtuxe of an inext oxganic diluent and alkali metal hydxoxide. Then, ethylene oxide or anothex su~stituent is added to the xesultant alkali cellulose and once the reaction is completed the product iæ txeated with nitxic acid. To this reaction mixture is added the alkyl glycidyl ethers and, optionally, a second incxement of ethylene oxide. Aftex the xeaction is co~plete, the product is then neutxalized, filtexed, washed with aqueous inext diluents and dried.
Since mixed hydxophobe polymexs genexally contain a shoxt chain hydxophobe in place of some of a longex chain hydxophobe, theix foxmation is moxe efficient and, thexefore, more economical.
Prepaxation of modified cellulose ethexs per this invention is demonstxated in the following preparation examples. Thxoughout this specification, all pexcentages, paxts, etc., are by weight unless otherwise indicated.
~-rALASIU~ '~A~L~ ~
This example shows prepaxation of C8/C16 mixed hydxophobe hydxoxyethylcellulose.
A solution of sodium hydroxide (25.6 paxts) in watex (86.5 paxts) was pxepaxed and added under nitrogen to a well agitated sluxxy of cellulose ~Gxade 502, 84 paxts "as is") in a mixture of t~bu~yl alcohol ~640 paxts), acetone (35.2 paxts) and isopxopanol (28 paxts) in a Chemco xeactor over a pexiod of 10 minutes. The xesulting mixtuxe was vigorously mixed at 24C fox 45 minutes. Then ethylene oxide (27.3 paxts) was added to the alkali cellulose sluxxy. Aftex heating at 70C fox 1 houx, the xeaction mixtuxe was cooled to 60C and txeated with 70~ nitxic acid (48 paxts). The paxtially neutxalized xeaction mixtuxe was cooled to 40C.

~ 32q5qo ~ 6 ~

Then additional ethylene oxide (70.6 parts) w~s added to the mixture and the mixture was heated with agitation to 90~95C
and held for 1.5 hours.
Subsequently, a solution of sodiu~ hydxoxide (2008 paxts) in watex (20.8 parts) was added to the hydxoxyethyl-cellulose reaction mixtuxe at 90~95C ovex a pexiod of 5 minute-~. Then, a mixtuxe of octyl and cetyl bxomide ~5 parts each) was added ovex a pexiod of 5 ~inutes. The resulting reaction mixture was heated at 115C fox 2 houxs. Then, it --was cooled to 55C and neutxalised with 70~ nitxic acid (53 paxts). ~he resultant product was purified by xepeatedly wa~hing the crude polymex with 80:20 acetone/water mixtuxe.
Afte~ purification, the polymer was dxied in a fluid bed dxyex at 50-60C. The resulting pxoduct had a hydroxyethyl M.S. of 3.2, 0.95% of a C8 hydrophobe and 0.35% of a C16 hydxophobe, both by weight of the total polymer, and a 1%
Bxookfield viscosity at 30 xpm of 310 cps.
PR~rARASI0~ EXAMPIE 2 T~is example shows prepaxation of C12/C16 mixed hydxophobe hydxoxyethylcellulose.
A hydxoxyethylcellulose xeaction mixture was prepared as described in Pxepaxation Example 1~ Then, a solution of sodiu~ hydroxide (20.~ paxts) in watex (20.8 parts) was added to the ~ixture at 90-95C over a period of 5 minutes followed by the addition of a mixture of lauryl and cetyl bromide (-5 paxts 0ach). The xesulting xeaction mixture was cooled to 55C, neutralized with 70~ nitric acid (53 parts), and purified and dried as described in Preparation Example 1.
The resultiny product had a hydxoxyethyl M.S. of 3.2, 0.6~ of a C12 hydxophobe and 0.3~ of a C16 hydxophobe, both by weight of the total poly~ex, and a 1% Brookfield viscosity at 30 rpm of 400 cps.
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This example shows preparation of C8/C12 mixed hydxophobe hydroxyethylcellulose.
To a mixture of t~butyl alcohol (689 parts), acetone ~24 parts) and a solution of sodium hydroxide (27.4 paxts) in watex ~100 paxts) was added chemical cotton (Grade 337, 84 parts "a~ is"). The xesulting mixture was vigorously stirred .
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t 329590 at 24C fox 45 ~inut~s. Then ethylene oxide (27.3 parts) ~as added to the alkali cellulose. After heating at 70C for 1 houx, the xeaction ~ixtuxe was cooled to 60C and treated with 70~ nitxic acid (48 parts). The paxtially neutxalized xeaction mixtuxe was cooled to 40C. To this xeaction mi~tuxe was added ~ore ethylene oxide (70.3 parts). The xesulting xeaction ~ixtuxe was heated at 95C fox 1.5 hours to form a hydxoxyethylcellulose pxecuxsox.
To the above xeaction mixtuxe containing hydxoxyethyl-cellulose at 95C was added a 50% solution of sodium hydxoxide (38.6 paxts) in watex ovex a pexiod of 5 minutes, followed by the addition of a mixtuxe of octyl ~4 parts) and lauxyl (5 paxts) bxomide. I'he xesulting ~ixtuxe was heated at 115C fox 2 houxs. Then, the xeaction mixtuxe was cooled to 55C and neutxalized with 70% nitxic acid (50 paxts~. The cxude poly~ex was puxified by washing with a 80:20 acetone/water mixtuxe. The xesulting pxoduct was analyzed and found to have the following pxoperties: H.E.M.S. 3O47 C8 hydxophobe D.S. O.C14 (0.52 wt %, based on the weight of the polymer), C12 hydrophobe D.S. 0.014 (0.74 wt %, based on the weight of the polymex), and Bxookfield viscosity (1%
solution at 30 rpm) of 270 cps.

This example shows pxeparation of C7/C15 16 3-alkoxy-2-hydxoxypxopylhydxoxyethylcellulose (hexe, the alkyl gxoups have 4, 12 and 13 caxbon atoms and the pxopyl gxoup accounts fox the 3 othex caxbon atoms in the hydxophobes).
To a ~ixtuxe of 689 parts t-butyl alcohol, 24 paxts acetone and a solution of 27.4 paxts sodiu~ hydxoxide in 100 paxts water was added che~ical cotton (Gxade 337, 84 paxts "as is"). The xesulting ~ixture was vigorously stixxed at 24C fox 45 minutes. Then, 27.3 paxts ethylene oxide was added to the alkali cellulose. Aftex heating at 70C fox 1 houx, the xeaction mixture was cooled to 55C and txeated with 48 paxts 70% nitxic acid. To this xeaction mixtuxe was added a second incxe~ent of 70.3 paxts ethylene oxide, 12 paxts of a C12_13 alkyl glycidyl ether (available undex the - 1 32q5~0 registered trademaxk Heloxy WC-9, from the Wilmington Chemical Corporation, Wilmington, DE~ and 12 parts of n-butyl glycidyl ether (available from Aldxich Chemical Company, Inc., Milwaukee, WI). The resulting reaction mixtuxe was heated at 95C for 90 ~inutes and then 115C for 2 hours.
After cooling the reaction mixture to room tempexatuxe, it wa~ neutralized with 10 parts 70~ nitric acid. Next, the xeaction mixture was filtered and the filtered cake ~aq wa6hed several time~ with 80:20 acetone/water mixtuxe to xemove salts and othex by-pxoducts. The xesultant polymex was characterized as C7/C15 16 3-alkoxy-2-hydroxypx3pyl hydxoxyethylcellulose having a 1~ Bxookfield viscosity at 30 rpm of 520 cps and a cloud point ~15~ NaCl solution) of 25C.
In anothe~ e~bodiment of this invention, the cellulose ether of this invention i~ further substituted with a third long chain alkyl radical having 6 to 20 carbon atoms, having a different carbon chain length than the othex two long chain alkyl radicals. Exemplaxy is hydxoxyethylcellulose having C8, C12 and C16 long chain alkyl groups, such as that shown in the following examples, which are not intended to be limiting.

This example shows preparation of a C~/C12/C16 mixed hydrophobe hydroxyethylcellulose.
The procedures of Pxepaxation Example 3 were xepeated with addition of cetyl bxomide (1 part) at the time of addition of octyl and lauryl bromide. The xesulting pxoduct had a H.E.M.S. of approximately 3.4, C8 hydrophobe D.S. of 0.C15 t0.54 wt. %, based on the weight of the poly~er), C12 hydrophobe D.S. of 0.011 ~0.62 wt. ~, based on the weight of the polymex), C16 hydrophobe D.S. of 0.003 (0.2 wt. %, based on the weight of the polymex) and ~xookfield viscosity ~1% solution at 30 rpm) of 380 cps.

This example shows pxeparation of a C8/C12/C16 mixed hydxophobe hydxoxyethylcellulose.

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1 32~5~0 g The proceduxes of Pxeparation Example 6 wexe repeated with addition of DOWF ~ 2Al anionic alkylated (C12) diphenyl oxide disulfonated surfactant (Dow Chemical Company, Midland, MI) (5 parts) along with the alkyl bromides and heating the resulting xeaction mixture at 115C for 1.5 hours. The resulting pxoduct had a H.E.M.S. of 3.5, a C8 hydrophobe D~S. of 0.38 (0.38 wt. %, based on the weight of the polymex), a C12 hydrophobe D.S. of 0.01 (0.52 weight %, based on ~he weight of the polymex), a C16 hydrophobe DuS.
of 0.002 (0.14 weight %, based on the weight of the polymex) and a Bxookfield YiSCosity (1% solution at 30 rpm) of 15G cps.
The cellulose ethexs of this invention are useful as viscosifiers for, among other things, latex paints. The amount of each of the hydrophobes having a different number of carbon atoms per this invention is dependent on the length of the backbone of the cellulosic derivative/ the degree or molax substitution of the hydroxyethyl, hydroxypropyl and/or methyl substituent (e.g., the hydroxyethyl molax substi-tution), th~ carbon number of each of the hydrophobes, the composition of and desired viscosity oE the product in which it is intended to be used, etc. Generally, the weight ratio of the long chain alkyl radicals will fall in the range of about 1:20 to 20:1. While a two carbon atom diffexence may be satisfactory to achieve the desired product in some instances, in other instances a three, four ox gxeatex carbon atom diffexence may be prefexred.
When alkyl bromide substituted polymexs axe compaxed, best latex paint perfoxmance propexties occur with hydroxy-ethylcellulGse having G.85 to 1.0 wt% C8 hydrophobe, 0.35 to 0.40 wt% C16 hydrophobe, and a viscosity of 300 to 400 cps 1% Brookfield Viscosity (at 30 RPM, spindle #2~ and hydroxyethylcellulose having 0.6 wt~ C12 hydrophobe, 0.3 to 0.35 wt~ C16 hydrophobe, and 300 to 400 cps 1~ Brookfield Viscosity, wherein all weight perrentages are based on the weight of the total polymeru The hydroxyethyl molax substitution (number of moles of hydroxyethyl unit per mole of anhydroglucose unit) of the hydxoxyethylcellulose is not critical to paint performance.

~~~" 132qsqn The pxincipal ingredients of watex-soluble pxotective coating compositions pex this invention axe film-foxmer latices selected fxom the group consisting of styrene-butadiene copolymexs, vinyl acetate polymers and copolymexs, and acrylic polymexs and copoly~exs (the ~ost prefexred of which are acrylic and vinyl acetate - acrylic in the United States, and ~tyxene acrylics and VeoVa acetate (al~o known as vinyl acetate-vinyl vexsatate) in Euxope), opacifying pigments, dispersing agents and watex-soluble protective colloids.
Typically, aqueous pxotective coating co~po~itions contain, by weight of the total composition, fxom about 10 to about 50% of a latex, fxom about 10% to about 50% of an opacifying pigment (e.g., Tio2, clay, calcium carbonate, silica, talc, etc.), fxom about 0.1% to about 2~ of a dispersant/suxfactant ~e.g., polyacxylates, potassium txipolyphosphate, 2-amino-2-methyl-1-propanol, etc.) and fxom about 0.1~ to about 1% of the polymexs of this invention.
Othex common ingredients include defoamers, pxeservatives, suxfactants, coalescing agents (eOg., glycols and glycol ethexs, etc.), etc.
The invention is illustxated in the following examples, which axe not intended to be limiting.

_-- .
Aqueous solutions comprising 1~, by weight, of C8/C16 hydxophobe hydroxyethylcellulose (polymexs iden-tified in Table 1) wexe pxepared by dissolving 1 g of the polymex in 99 g distilled water. Then, the 1% Bxookfield Viscosity (at 30 xpm) of the solution was detexmined. The polymex compositions and viscosities axe shown in the following Table 1.

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G ~ > ~d ~rl rl ~) ~rt t ~ ~t ~-t l-t~-t C,~ I-t ~ C 3 3 ~t 3 . . _ _ _ _ _ _ _ _ _, _ r~ rt r;

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~ 329590 The above xesults show that a polymex having 1 weight C16 polymex is not soluble in water (Sample 8. See also Sample 20.), whereas use of a mixed hydrophobe system pexmits prepaxation of water-soluble polymexs having 1 or ~oxe weight ~ hydrophobe (Examples 9-14 and 16-19).
The use of a mixed hydrophobe system also gives the pxactitioner an added degree of xehology contxol than is obtained using a single hydxophobe. For :instance, Sample 15 containing 1.9 weight ~ of a C~ hydrophobe had a Bxookfield viscosity of 98 cps, whereas Sample 14 having 1.7 weight ~ of a C8 hydxophobe and 0.17% of a C16 hydxophobe ~ad a Brookfield viscosity of 415 cps and Sample 16 having 1.7 weight % of a C8 hydxophobe and 0.25 weight % of a C16 hydxophobe had a viscosity of 2520 cps.
Paints pxepaxed with polymexs having hydxophobic xadicals have supexiox colox development pxopexties (change in colox due to sheax) as compaxed to the unmodified equivalents, e.g., hydxoxyethyl cellulose. Furthex, longex hydxophobes pxovide superiox colox development properties as ~0 compaxed to shoxtex hydrophobes. Howevex, there is a limit to the amount of long chain hydxophobe that can be incoxpoxated to a polymer, i.e., if too much of a hydxophobe is intxoduced into a polymer the polymex becomes insoluble in water. The inventox has discovexed that this solubility limitation can be ovexcome by use of a mixed hydxophobe system according to this invention and that paints containing mixed hyxdophobes have supexior colox development propexties as compaxed to those pxepaxed with single hydxophobes.
Fuxthex, spattex resistance is dependent on hydxophobe substitution level (the specific level desi~ed depends upon the degxee o polymexization). Thus, the mixed hydxophobe systems enable the practitionex to use the pxopex ~evel of hydxophobe substitution to obtain impxoved spattex resistance propexties, without intxoducing color development pxoblems.
~ 2~
An intexiox semi~gloss paint was prepaxed using Rhoplex AC-417 latex (Rohm and Haas Company, Philadelphia, PA).
First, the following wexe mixed fox 30 minutes at high speed with a Cowles blade:

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t 32~590 Table 2 Pxopylene Glycol 140.00 Tamol SG-l dispex~antl 14.90 5 Hercules SGL Defoa~lex2 3.50 Water 43 75 Ti-Puxe R-900 pigment3 420.00 Silica 1160 e~tendex pigment4 43.75 ~ Haas Co~pany, Philadelphia, PA.
2. Available fxoM ~excules Incorpoxated, Wilmington, DE.
3. Available fxom E. I. du Pont de Nemouxs & Company, Inc., Wilmington, DE.
4~ Available from Illinois Minexals Company, Caixo, IL.
Then, the following wexe added and the batch was mixed fox 30 ~inutes at xeduced speed with a pxopellex bladeO

Table 3 Co~ponent Hexcules SGL Defoamexl 4.75 Pxopylene Glycol 17.50 Texanol coalescing agent237080 Supex-Ad-It presexvative2 1.75 Triton GR 7M suxfactant30.90 Rhoplex AC-417 875.00 .
~ es Incoxpoxated, Wilmington, ~E.
~. Available fxom Eastman Chemical Pxoducts, Kingspoxt, IN.
3. Available fxo~ Roh~ & ~aas Company, Philadelphia, PA.
The above base paint was then thickened to an initial viscosity shown in the following Table 4 with 297 total paxts of (a) an aqueous thickenex solution containing the polymer listed in Table 4 and (b) watex.
Colox development was measuxed by a subjective test, using the paint tinted with a thalo blue coloxant. The colo~
between a xubbed and unxubbed axea of a test caxd was rated on a scale of 0 (no diffexence) to 4 (rubbed axea vexy much daxkex).

' ~ 3~q59 To a 1/2 pint lined paint can, was add~ 98 gxams of thickened paint and 2.0 grams of Coloxtxen ~ thalo blue colorant (~uodex, Inc., Piscataway, NJ). Then, the paint was shaken for 5 minutes using a Red Devil Shaker. Afterwards, using a 5 mil dxawdown blade, a portion of the paint was dxawn ovex a plain white chaxt, Form WB (available from the Leneta Company, Ho-Ho-Kus, ~J). The bottom tunsealed~
portion of the paint film was rubbed u~ing a circulax motion, until the film was tacky. This shows pexfoxmance undex high sheax conditions. Thxee minutes latex, the top (sealed-portion) was xubbed in the same mannex. This shows pexformance under low shear conditions. The cards wexe hung to dxy and, then, were evaluated for color difference, with the specification being based on the rating of the unsealed portion of the card.

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The data in Table 4 demonstrate that paints pxepaxed with the polymexs of this invention have supexiox color development properties to those pxepaxed with polymers only having one C16 hydxophobe. The polymer of Example S having 1~ by weight of a C16 hydrophobe is insoluble in water and, thus, is not useful in a latex paint. The polymex used in Example 22, having 0.72% by weight of a C16 hydrophobe, is soluble in the watex, but produces a paint with compaxatively poor color development propexties. In contxast, the paint of Example 21, pxepared with a polymer having a mixed hydxophobe sy~tem per this invention (1.20% total hydrophobej, has supexior colox development pxopexties to th paint of Example 22.
The polymexs of this invention axe useful as noted above and as stabilizers in emulsion polymexization, as protectiv,e colloids in suspension polymexization, as thickenexs in co~metics and shampoos, and as flocculants in minexal pxocessing, etc.

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Claims

1. A water-soluble, cellulose ether polymer having (a) at least one substituent selected from the group consisting of hydroxyethyl, hydroxypropyl, and methyl radicals and (b) two or more hydrophobic radicals having 6 to 20 carbon atoms selected from the group consisting of long chain alkyl, alphahydroxyalkyl, urethane, acyl and 3-alkoxy-2-hydroxypropyl, characterized in that one of the hydrophobic radicals has a carbon chain length that is at least two carbon atoms longer than that of another of the hydrophobic radicals, the hydrophobic radicals are contained in a total amount of at least about 0.2 weight percent, and the cellulose ethers are at least 1% by weight soluble in water.

2. The cellulose ether polymer of claim 1 wherein one of the hydrophobic radicals has a carbon chain length that is at least four carbon atoms longer than that of the other of the hydrophobic radicals.

3. The cellulose ether polymer of claim 1 which is anionic or nonionic.

4. The cellulose ether polymer of claim 1 which is nonionic.

5. The cellulose ether polymer of claim 1, 2, 3 or 4 wherein one of the hydrophobic radicals contains 12 or more carbon atoms.

6. The cellulose ether polymer of claim 1, 2, 3 or 4 wherein one of the hydrophobic radicals contains 15 or more carbon atoms.

7. The cellulose ether polymer of claim 1, 2, 3 or 4 wherein one of the hydrophobic radicals contains 8 or less carbon atoms.

8. The cellulose ether polymer of claim 5 wherein one of the hydrophobic radicals contains 8 or less carbon atoms.

9. The cellulose ether polymer of claim 1, 2, 3 or 4 wherein the polymer contains two hydrophobic radicals.

10. The cellulose ether polymer of claim 8 wherein the polymer contains two hydrophobic radicals.

11. The cellulose ether polymer of claim 2 which is nonionic or anionic.

12. The cellulose ether polymer of claim 2 which is nonionic.

13. The cellulose ether polymer of claim 10 which is nonionic.

14. The cellulose ether polymer of claim 1, 2, 3 or 4 wherein the polymer contains three hydrophobic radicals, each of which has at least two carbon atoms more or less than the others.

15. The cellulose ether polymer of claim 14 which is nonionic and wherein (a) one of the hydrophobic radicals contains 8 or less carbon atoms and (b) a second of the hydrophobic radicals contains 12 or more carbon atoms.

16. The cellulose ether of claim 1 wherein the substituent (a) is a hydroxyethyl radical.

17. The cellulose ether of claim 2 wherein the substituent (a) is a hydroxyethyl radical.

18. The cellulose ether of claim 13 wherein the substituent (a) is a hydroxyethyl radical.

19. The cellulose ether of claim 1 wherein the substituent (b) is an alkyl radical.

20. The cellulose ether of claim 18 wherein the substituent (b) is an alkyl radical.

21. The cellulose ether of claim 1 wherein the substituent (b) is a 3-alkoxy-2-hydroxypropyl radical.

22. The cellulose ether of claim 18 wherein the substituent (b) is a 3-alkoxy-2-hydroxypropyl radical.

23. The cellulose ether polymer of claim 6 wherein another of the hydrophobic radicals contains 8 or less carbon atoms.

24. Use of the water-soluble, cellulose ether polymer as claimed in any one of claims 1 to 3 as a thickening agent in an aqueous protective coating.